Nara has really hit her stride recently, with her last six months including third round outings at the US Open and Australian Open and her first WTA semifinal showing in Osaka. And now the Japanese No.1 finds herself a win away from another semifinal.

In her match with Friedsam, Nara did not surrender a game and lost just nine points in the first set. She staged a mini rally from 4-2 down in the second set and eventually forced a tie-break, where from 3-2 down she won five straight points for the 60 76(3) triumph. Her first win in three tries against Friedsam featured a 23-minute first set and an hour-and-18-minute second set.

"I'm very happy to win and make the quarterfinals. It's special," Nara said. "I'm enjoying this tournament. I used to not like clay courts but they've grown on me. I also like the hot weather."

Next up for Nara is Lourdes Domínguez Lino, who survived a battle with Chanelle Scheepers. The Spaniard was down a set and 5-2 and fought off two match points at 5-4 and another in the tie-break, eventually going on to a 26 76(7) 61 victory.

"I started very well," Pereira said. "I was aggressive and she was missing a lot. And then she started to play better, so I'm really happy to get the victory. The crowd was unbelievable. I'm enjoying playing here in Brazil."

Among those booking quarterfinal spots in doubles were No.1 seeds Barbora Zahlavova Strycova and Klara Zakopalova, who won 's-Hertogenbosch in 2011 the last time they teamed up. Zakopalova is also seeded first in singles and will play her quarterfinal match against Katarzyna Piter on Friday.